TW201807770A - High power electrostatic chuck design with radio frequency coupling - Google Patents

Abstract

An electrostatic chuck is described that has radio frequency coupling suitable for use in high power plasma environments. In some examples, the chuck includes a base plate, a top plate, a first electrode in the top plate proximate the top surface of the top plate to electrostatically grip a workpiece, and a second electrode in the top plate spaced apart from the first electrode, the first and second electrodes being coupled to a power supply to electrostatically charge the first electrode.

Description

High-power electrostatic chuck design with RF coupling

Cross-reference to related applications: This application claims to US Provisional Patent Application No. 62 / 352,667, filed on June 21, 2016 and entitled "HIGH POWER ELECTROSTATIC CHUCK DESIGN WITH RADIO FREQUENCY COUPLING" by Jaeyong Cho et al. And claims priority to US Provisional Patent Application No. 62 / 346,746 filed by Jaeyong Cho et al. On June 7, 2016, entitled "HIGH POWER ELECTROSTATIC CHUCK DESIGN WITH RADIO FREQUENCY COUPLING".

This description relates to electrostatic chucks for carrying workpieces for semiconductor and micro-electromechanical processing, and in particular to electrodes in the chuck.

During the production of semiconductor wafers, silicon wafers or other substrates are exposed to various processes in different processing chambers. The chamber exposes the wafer to several different chemical and physical processes to create small integrated circuits on the substrate. The material layer constituting the integrated circuit is produced by a process including chemical vapor deposition, physical vapor deposition, barrier crystal growth, and the like. Use photoresist masks and wet (or dry) etching techniques to pattern some material layers. The substrate may be silicon, gallium arsenide, indium phosphide, glass or other suitable materials.

In these production processes, a plasma can be used to deposit or etch various material layers. Plasma treatment offers many advantages over heat treatment. For example, compared to a comparative thermal process, plasma enhanced chemical vapor deposition (PECVD) allows the deposition process to be performed at lower temperatures and higher deposition rates. Therefore, PECVD allows material to be deposited at lower temperatures.

The processing chambers used in these processes typically include a substrate support, base, or suction cup placed in the processing chamber to support the substrate during processing. In some processes, the base may include a built-in heater that is adapted to control the substrate temperature, and / or provides an elevated temperature that can be used in the process.

HAR (high aspect ratio) plasma etching uses a much higher bias power to achieve a bend-free profile. In order to support HAR for dielectric etching, the power can be increased to 20KW, which has a significant impact on ESC (electrostatic chuck). Many current ESC designs cannot tolerate such high voltages directly from high bias power. Holes designed in ESC are particularly vulnerable. Furthermore, ESCs can experience joint failure in the area of the lift pin when excessive free radicals attack the joint. Another kind of impact is that ESC surface temperature changes at a higher rate. The heating of the ESC surface is directly proportional to the RF plasma power applied. Heat can also be the result of joint failure. In addition, the warpage of the wafer carried on the ESC and the charge built on the wafer also make the desorption of the wafer more difficult.

A common process using ESC to hold wafers is to apply 2MHz 6.5KW plasma power to the wafer for etching applications. Applications with high aspect ratios (eg 100: 1) use much higher plasma power. This article describes operating in low frequency, high power plasma voltages to produce ESCs with high wafer bias. Higher power will increase the chance of ESC failure due to dielectric breakdown and plasma ignition in the pores of the ESC. The illustrated ESC can withstand high power and high bias voltages.

An electrostatic chuck having an improved electrode will be described. In some examples, the suction cup includes a base plate, a top plate, a first electrode adjacent to the top surface of the top plate in the top plate to hold the workpiece electrostatically, and a second electrode spaced from the first electrode in the top plate, the first and second electrodes. The first electrode is coupled to a power supply to electrostatically charge the first electrode.

In some embodiments, a two-layer grid is formed (or added) in a ceramic top plate of an electrostatic chuck (ESC). Compared to the upper grid, the design of the lower grid has been modified to allow higher plasma power and frequency when the chuck holds a workpiece (such as a silicon wafer) during processing. The suction cup can be formed in various ways.

The higher voltage in the plasma can cause electrostatic discharge in the top plate or disc of the suction cup. Using a two-layer grid of electrodes in the disc, a non-discharged Faraday cage can be formed in the disc.

Fig. 1 is a cross-sectional side view of an electrostatic chuck, wherein a double grid electrode is provided in the upper disc. In the illustrated example, the suction cup is an ESC with an aluminum cooling plate or base plate. The disc 206 is bonded to the base plate by a dielectric adhesive layer 204. The adhesive layer attenuates electrical and thermal conduction between the disc and the substrate. The disc is made of ceramic or another dielectric. The disc uses electrostatic forces to hold a workpiece, such as wafer 208. This article will refer to the workpiece as a wafer, although the chuck can carry other workpieces for a variety of different products and processes. The diagram is simplified to avoid obscuring the features of the invention.

The base plate may contain many other components, features, and external connections for thermal fluids, airflow, heater power, sensors, and other components. Similarly, the disc may contain heaters, sensors, liquid and air channels, and other features connected to external components through a base plate. There may be additional boards under the illustrated base plate to provide physical support and to carry some of these other components. Although there may be many other additional features, there may be a single central tube 230 passing through the base plate and the top plate of the chuck to carry a cooling and thermally conductive gas (such as helium) from the backside of the wafer through the chuck. There may be additional air holes and other holes. Additional holes 232 through the base plate and the wafer may provide lifting pins to, for example, push the wafer away from the chuck to desorb.

The upper electrode 212 (such as a wire grid or plate near the top surface of the disk) is used to generate an electrostatic force holding the wafer 208, which is applied from an external power supply 222 through an electrical connector or rod 220 that passes through the base plate and the disk. Voltage to the wire grid to charge the upper electrode 212. The external power supply can be AC (alternating current) or DC (direct current) power. The line grid 212 appears as lines near the wafer in this cross-sectional side view. In a top view, the grid is a network of generally orthogonal crossing lines that covers most of the area near the top surface of the disc. The wire can be copper, aluminum or molybdenum. Alternatively, the line grid may be a solid (or mostly solid) conductive plate embedded in a disc. The board can have several parts to apply different electrostatic polarities or charge amounts. The top grid 212 and the bottom grid 210 can be made by screen printing, deposition or rotation. Alternatively, the conductive sheet may be individually cast or machined and then placed into the top plate when it is formed.

The on-line grid can also be coupled to an external RF (radio frequency) power generator 224 through the electrical connector 220 to induce a bias voltage on the wafer and cause ion bombardment on the wafer. The RF power supply 224 may be the same or different from the DC voltage source 222. The connector 220 of the upper grid 212 may be the same connector (or two or more different connectors) connected to the same upper grid.

As mentioned above, the disc has a dual grid or dual electrodes. The lower grid 210 is added below the main upper grid 212. A series of bolts 214 are used to electrically connect the lower grid to the voltage supply. The bolts 214 are connected between the upper grid and the lower grid and carry the same voltage potential and RF power. From an RF power coupling point of view, the dual grid makes the equivalent thickness of the dielectric thinner while maintaining the thermal U% benefit of the thicker dielectric material. U% in this context represents the amount of uniformity. The double grid also reduces or eliminates the electric field gradient between the upper and lower grids.

By using the pegs 214 to connect the two grids 210, 212, the double grid can prevent the helium in the disc from igniting. Helium ignition is caused by an electric field generated by RF power coupled to a single grid electrode embedded in a ceramic plate. This is an upper electrode for holding a wafer with an electrostatic force. The lower grid creates a Faraday cage within the disc between the upper and lower grids. All channels, holes and gaps (not shown) in the area between the upper and lower grids will be shielded from any accumulated charge. The upper grid is as close to the top of the disc as possible to provide better electrostatic grip. The lower grid is as close as possible to the bottom of the disc to provide a larger Faraday cage.

Figure 2 is a cross-sectional side view of an alternative embodiment of a dual grid shield. As in the example of FIG. 1, the disk 306 or the top plate is attached to the base plate 302 by the insulating adhesive layer 304. The base plate is usually aluminum, while the top plate is usually ceramic (such as alumina), although other materials can be used. Among other features, there are a central air hole 330 and a lift pin hole 332. As shown in the example in FIG. 1, the disc has an upper grid 312 and a lower grid 310, and the upper grid 312 and the lower grid 310 are electrically connected together by a bolt 314 or any other suitable electrical connector. The grids and pegs are embedded in the ceramic when the ceramic is fired, however, the grids and pegs may be attached or formed by other means instead. The upper grid provides an electrostatic charge to hold the wafer 308 to be processed. As shown in Figure 1, the offline grid is electrically connected to the voltage supply and carries the same voltage potential.

In the example of FIG. 2, two grids are coupled to a voltage source 322 through an electrical connector in the form of a rod 320 passing through a channel in the base plate 302. The RF power supply 324 is coupled to the base board 302 using an electrical connector 326. The RF power generator induces a bias voltage on the wafer and causes ion bombardment on the wafer.

The dual-grid function is the same as in the previous example, in order to prevent any charge buildup by shielding the part between the two grid layers in the disc to prevent ignition of any gas or other material in this part of the disc. In addition, the dual grids 310, 312 enhance the conduction of RF power 324 from the cooling plate through the disk 306 to the wafer 308. The conductive grids 310 and 312 and the base plate 302 serve as capacitor plates. These capacitor plates are separated from the ceramic material of the disc 306 by a dielectric adhesive layer 304. By lower grid 310 and placing the lower grid close to the base plate, this capacitance value is reduced. By applying a DC voltage similar to the DC voltage applied to the disc electrostatic electrodes 310, 312 to the base plate, the capacitance value is also reduced. This DC potential can be applied to a substrate plate in any of the examples described herein.

The dual grid structure significantly reduces the capacitance and impedance between the cooling plate and the wafer through the disk. Equivalently, the dual grid reduces the dielectric thickness of the disc in order to couple RF power through the disc. While maintaining the thermal U% benefits. On a real wafer in a plasma etch chamber, this can increase the etch rate by 10% or more.

FIG. 3 is a cross-sectional side view of an alternative embodiment of a dual-grid shield in which a negative voltage is applied to the cooling plate to reduce the potential difference between the workpiece and the cooling plate. As in the example of FIG. 1, the ceramic disc 406 is attached to the aluminum base plate 402 by the adhesive layer 404. The disc has an upper grid 412 and a lower grid 410 embedded in the disc, and the upper grid 412 and the lower grid 410 are connected by a bolt 414. As shown in Figure 1, the offline grid is electrically connected to the voltage supply and carries the same voltage potential. Among other features, the assembly has a central air hole 430 and a lift pin hole 432.

In the example of FIG. 3, two grids are coupled to a voltage source 422 through a rod 420 passing through a base plate 402. An RF power supply (not shown) can also be coupled to the disc to induce a bias voltage on the wafer. The second RF power supply 424 is also coupled to the base board 402 using an electrical connector 426. In addition, a DC voltage 440 is coupled to the base plate. The DC power supply 440 and the RF power supply 424 may be the same or separate (as shown).

The DC potential on the base plate reduces the potential difference between the base plate and the wafer. The electric power applied to the DC electrode does not generate a DC discharge because the electrode is embedded in the ceramic. This prevents secondary electrons from being emitted from the electrodes while maintaining DC discharge. On the other hand, there is a potential difference between the wafer and the cooling plate. The potential on the wafer is generated by the RF power applied to the electrodes in FIG. 1 or the base plate in FIG. 2.

As an example, if an adsorption voltage of -4kV is generated on the electrostatic electrode, the potential difference will be 4kV or more. If the voltage of the base plate is allowed to float, the difference can be even greater. On the other hand, by applying a voltage of about -2kV to the base plate, the potential difference can be reduced by half (about 2kV). The reduced capacitance value provides more control of the plasma process parameters, and further reduces the arcing effect in the air holes in the base plate and disc. Higher voltages can be applied to the substrate, up to and including the wafer voltage (-4kV in this case), but the voltage can be another voltage. This reduces the electric field across the disc.

Fig. 4 is a cross-sectional side view of a variation of the sucker of Fig. 1 having a double grid. In this example, the suction cup is also an ESC with a cooling plate 202. The disc 206 is bonded to the base plate by a dielectric adhesive layer 204. The disc holds the workpiece 208 using an electrostatic force. A single central tube 230 passing through the base plate and the top plate of the chuck carries a cooling and thermally conductive gas (such as helium, nitrogen, or some other gas) from the wafer back side through the chuck. The extra holes 232 through the base plate and the wafer carry the gas, or contain lifting pins to push the wafer away from the chuck to desorb.

The upper electrode 212 is used to generate an electrostatic force holding the wafer 208, and the upper electrode 212 is charged by applying a voltage from an external power supply 222 to the lower electrode 210 through an electrical connector or rod 220 passing through the base plate and the disc. The bottom electrode 212 may also be coupled to an external RF (radio frequency) power generator 224. As shown, the connector rod 260 is directly connected to the lower electrode 210 instead of the upper electrode 212 as shown in FIG. 1.

A series of pegs 214 are used to electrically connect the lower electrode 210 to the upper electrode 212, and the pegs 214 are connected between the upper and lower electrodes so that the upper and lower electrodes carry the same voltage potential and RF power. As shown in the example in FIG. 1, the electrodes 210 and 212 connected by the pegs 214 can prevent the ignition of helium in the disc and other electrostatic discharge effects by means of a large Faraday cage.

Fig. 5 is a modified cross-sectional side view of the suction cup of Fig. 1 having a double grid. The ESC has a cooling plate 202 and a disk 206 attached by a dielectric adhesive layer 20. The disc holds the workpiece 208, and various tubes or holes 230, 232 passing through the chuck base plate 202 and the top plate 206 provide access through the disc to the back side of the wafer.

In this example, there is a first connector or rod 220 to the upper electrode 212 in the disc, and a second connector or rod 262 to the lower electrode in the disc. These poles all apply voltage from the same external power supply 222 and an optional external RF (radio frequency) power supply 224. The two poles directly connect the two electrodes to the same power supply, however, different power supplies may optionally be used.

In addition, the lower electrode 210 is optionally electrically connected to the upper electrode 212 using a series of pegs 214 connected between the upper and lower electrodes. As in the example of Figure 1, the connected electrodes 210, 212 form a large Faraday cage. Although the examples of FIGS. 4 and 5 use the power supply connection of the counter electrode of FIG. 1, the connection of FIG. 2 may be used instead.

FIG. 6 is a side sectional view of an example of the electrical connector 220 connecting the upper electrode 212 to the power supply. The rod extends through an opening (not shown) in the lower electrode. The rod has an upper portion 240 and a longer lower portion 242, the upper portion 240 is in contact with the electrode and is made of a high-resistivity material, and the lower portion 242 is made of a low-resistance material (such as aluminum or copper). The upper portion may be made of any of a variety of materials, such as aluminum mixed (or doped) with alumina powder. The concentration of alumina powder particles determines the resistivity of the rod. The high-resistivity material may have a resistance value of one thousand ohms or more, and the low-resistance portion may have a resistance value of less than one thousand ohms.

The high-resistance part of the rod is used to limit the current flow, specifically a large current surge through the rod. In use, the upper and lower electrodes may have a high charge induced by the plasma power in the chamber. By limiting the current flow, the current flowing through the rod to the power supply is limited. This protects the power supply. In addition, the charge induced on the electrode is more able to stay on the electrode, rather than flowing through the rod and generating a hot spot where the rod is connected to the electrode. With sufficient current, the rod can overheat, heating the disc and possibly destroying the disc. When using alumina ceramic discs, excessive heat will cause the disc ceramics to crack.

FIG. 7 is a partially transparent plan view of the disk 206 of FIG. 1. The disk has a lower electrode 210 and an upper electrode 212. The size of the lower electrode 210 is slightly larger than the wafer to be held, and the size of the upper electrode 212 is almost the same as the wafer to be held. The electrodes are located within the dielectric material of the disc, and the dielectric material is illustrated as transparent to make the electrodes visible. The form of the upper electrode 212 and the lower electrode 210 may be a small line grid, a coating, or a solid plate. The reference to the upper electrode 212 and the lower electrode 210 in this document will refer to these terms.

The electrodes are electrically connected to a series of connector pins 214. These pegs are illustrated as surrounding the perimeter of the upper electrode and connected just inside the lower electrode. The peg may be embedded and formed in the disc, or it may be formed of a solid or hollow conductive material and then fixed as the disc material cures. The pegs may surround the periphery of the upper electrode with equal or unequal spacing. The pegs are close enough to each other to form a Faraday cage to resist the expected RF energy expected in the processing chamber during the plasma process. In addition to the electrodes, there are a central air hole 230 and a lift pin hole 232. There may be additional holes and other structures to perform other functions. As shown in Figure 1, heaters, cooling channels, plasma process structures, and other components are not shown to avoid obscuring the pattern.

As shown, the holes 230, 232 are located within the periphery of the upper and lower electrodes. This keeps these holes in the Faraday cage (as mentioned above) and protected from external voltages, charges, and other conditions caused by high-energy plasma.

This specification discloses many details, but it will be apparent to those having ordinary knowledge in the field of the present invention that the present invention may be practiced without these specific details. In some instances, conventional methods and devices are illustrated in block diagram form, rather than in detail, to avoid obscuring the invention. References to "a specific embodiment" or "a specific embodiment" throughout this specification indicate that a particular feature, structure, function, or characteristic described with this specific embodiment is included in at least one specific embodiment of the invention. Therefore, the words "in a specific embodiment" or "in a specific embodiment" in the paragraphs throughout the specification do not necessarily refer to the same specific embodiment of the invention. Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more specific embodiments. For example, the first specific embodiment may be combined with the second specific embodiment, and specific features, structures, functions, or characteristics associated with the two specific embodiments are not mutually exclusive.

FIG. 8 is a side cross-sectional view of an electrostatic chuck having a reinforcing rod for supplying a suction current to an electrode. The illustrated conductive rod is adaptable for any other suction cup example. As shown in the other schematic diagrams, the base plate 502 supports a top plate 506 that uses a charge on the upper electrode 512 to electrostatically grip a workpiece, such as a silicon wafer. The rod 520 conducts current through the base plate to the electrode 512 to establish and dissipate a charge. The lower electrode 510 is coupled to the upper electrode through an array of vertical pegs 514. As mentioned above, due to the peg, the rod can be connected to the upper electrode, the lower electrode, or both the upper and lower electrodes. The electrodes and studs are embedded in the top plate, which is usually (but not necessarily) ceramic.

The base plate is thermally conductive and can have cooling channels, heaters, and other thermal control elements. Common thermally conductive materials are also electrically conductive, while aluminum is a common material used for substrate boards. In contrast, the top plate is dielectric to allow the top plate to maintain an electrostatic charge, and therefore generally also has a very low thermal conductivity. This is compensated by making the top plate very thin.

Because of these electrical characteristics, when the chuck is placed in an RF plasma, RF current tends to flow across the surface of the conductive substrate plate and through the top plate to the upper and lower electrodes. This illustration is an arrow traveling from the surface of the base plate through the top plate to the lower electrode. Since the electrodes are electrically connected, RF current flows freely through the two electrodes. RF current tends to be concentrated at point 522 of the grid connecting rod. The accumulated amount depends on the impedance of the plasma and the impedance of the rod. The rod is conductive and conducts current to the connected power supply, so RF current tends to flow down from the rod to the power supply, as shown by the arrow. When the rod also supplies RF current to the electrode, the concentration of the RF current increases. High RF current concentrations can cause arcing within the top plate, or arcing between the top plate and the workpiece.

The reinforced rod 520 as shown includes an inductor 524 that surrounds or couples to a portion traveling through the cooling plate 502. As in other examples herein, the inductor and the rod are electrically insulated from the conductive substrate by an electrical insulator 526, which is located within the hole through which the rod extends.

The inductor 524 may be in any of a variety of different forms, such as a coil, a cylinder, or a magnetic bead. The inductance value can be selected based on the expected frequency of the RF plasma. The inductor chokes or blocks the RF current generated by the applied RF plasma. This effect is illustrated by the arrow terminating at the inductor 524. The choke effect prevents the RF current from being concentrated at the connection point of the rod to the electrode. If the RF current is applied to the electrode from the power supply as shown in Figures 4 and 5, the inductance value is also selected to allow the supplied power to reach the electrode, while also blocking the RF current generated by the plasma.

If RF power is also applied to the adsorption electrode 512, it is very difficult to choose to block the RF current generated by the plasma from flowing into the rod, while allowing the RF power applied to the electrode to flow through the inductance value of the electrode to the wafer. This is because the plasma tends to be similar to the RF power applied. The inductor on the pole will also produce an impedance value, which is directly related to the frequency of the inductor trying to pass. For a coil inductor, the impedance value is defined by 2π × frequency × inductance value.

FIG. 9 is a partial cross-sectional view of a plasma system 100 having a base or suction cup 128 according to a specific embodiment described herein. The base 128 has an active cooling system. While the substrate placed on the base is subjected to various processes and chamber conditions, the active cooling system allows the temperature of the substrate to be actively controlled in a wide temperature range. The plasma system 100 includes a processing chamber body 102 having a side wall 112 and a bottom wall 116 that define a processing area 120.

A base, carrier, suction cup, or ESC 128 is placed in the processing area 120 through a channel 122 formed in a bottom wall 116 in the system 100. The base 128 is adapted to support a substrate (not shown) on the upper surface of the base 128. The substrate may be any of a variety of different workpieces for the processing process applied to the chamber 100, and is made of any of a variety of different materials. The base 128 may optionally include a heating element (not shown), such as a resistive element, to heat and control the substrate temperature to a desired process temperature. Alternatively, the base 128 may be heated by a remote heating element, such as a lamp assembly.

The chuck also includes a connected upper electrode and a lower electrode (not shown). The upper electrode and the lower electrode are embedded in the chuck to hold the wafer (not shown) to the top surface of the chuck. The suction cup includes an upper plate and a base plate, which is shown in more detail in FIG. 1.

The base 128 is coupled to the power socket or the power box 103 with a shaft 126. The power socket or the power box 103 may include a driving system that controls the lifting and moving of the base 128 in the processing area 120. The shaft 126 also includes a power interface to provide power to the base 128. The power supply box 103 also includes an interface for a power source and a temperature indicator, such as a thermocouple interface. The shaft 126 also includes a base assembly 129 adapted to be detachably coupled to the power box 103. The power supply box 103 is shown with a circumferential ring 135. In a specific embodiment, the circumferential ring 135 is a shoulder adapted to be a mechanical stop or region, and this shoulder is configured to provide a mechanical interface between the base assembly 129 and the upper surface of the power box 103.

A rod 130 is placed through the channel 124 formed in the bottom wall 116, and the rod 130 is used to activate the substrate lifting pin 161 placed through the base 128. The substrate lift pin 161 lifts the workpiece off the top surface of the base to allow the workpiece to be removed and moved into and out of the chamber. This usually uses a robot (not shown) that passes through the substrate transfer port 160.

The chamber cover 104 is coupled to the top of the chamber body 102. The cover 104 houses one or more gas distribution systems 108 coupled to the cover 104. The gas distribution system 108 includes a gas inlet channel 140, and the gas inlet channel 140 transmits the reactant and the cleaning gas into the processing chamber 120B through the shower head assembly 142. The showerhead assembly 142 includes a ring-shaped base plate 148, and the ring-shaped base plate 148 has a blocking plate 144 which is interposed between the ring-shaped base plate 148 and the panel 146.

A radio frequency (RF) source 165 is coupled to the showerhead assembly 142. The RF source 165 powers the showerhead assembly 142 to assist in generating a plasma between the panel 146 of the showerhead assembly 142 and the heating base 128. In a specific embodiment, the RF source 165 may be a high frequency radio frequency (HFRF) power source, such as a 13.56 MHz RF generator. In another specific embodiment, the RF source 165 may include a HFRF power source and a low frequency radio frequency (LFRF) power source, such as a 300 kHz RF generator. Alternatively, an RF source may be coupled to other parts of the processing chamber body 102 (such as the base 128) to assist in generating the plasma. A dielectric isolator 158 is placed between the cover 104 and the showerhead assembly 142 to prevent conducting RF power to the cover 104. A shielding ring 106 can be placed on the periphery of the base 128, and the shielding ring 106 engages the substrate at the desired height of the base 128.

Optionally, a cooling channel 147 is formed in the annular base plate 148 of the gas distribution system 108 to cool the annular base plate 148 during operation. The cooling channel 147 may be circulated through a heat transfer fluid, such as water, glycol, gas, or the like, to maintain the base plate 148 at a pre-defined temperature.

The chamber pad assembly 127 is placed in the processing area 120 and is very close to the side walls 101, 112 of the chamber body 102 to prevent the side walls 101, 112 from being exposed to the processing environment in the processing area 120. The gasket assembly 127 includes a circumferential pump cavity 125 coupled to the pump system 164, the circumferential pump cavity 125 being configured to discharge gases and byproducts from the processing region 120 and control the pressure within the processing region 120. A plurality of exhaust ports 131 may be formed on the chamber gasket assembly 127. The exhaust vent 131 is configured to allow gas to flow from the processing area 120 to the circumferential pump cavity 125 and to assist the processing process within the system 100.

The system controller 170 is coupled to various systems to control the manufacturing processes in the chamber. The controller 170 may include a temperature controller 175 to execute a temperature control algorithm (such as temperature feedback control), and may be software, hardware, or a combination of software and hardware. The system controller 170 also includes a central processing unit 172, a memory 173, and an input / output interface 174. The temperature controller receives a temperature reading 143 from a sensor (not shown) on the base. The temperature sensor may be close to the coolant channel, close to the wafer, or placed in a dielectric material of the base. The temperature controller 175 uses the sensed one or more temperature output control signals to affect the heat between the base assembly 142 and the heat source and / or a radiator (such as the heat exchanger 177) outside the plasma chamber 105. Transmission rate.

The system may also include a controlled heat transfer fluid circuit 141 that controls the flow of the heat transfer fluid circuit 141 based on the temperature feedback circuit. In an exemplary embodiment, the temperature controller 175 is coupled to a heat exchanger (HTX) / cooler 177. The heat transfer fluid flows through a valve (not shown) and passes through the heat transfer fluid circuit 141 at a rate controlled by the valve. Valves can be incorporated into heat exchangers, or pumps inside or outside the heat exchanger to control the flow rate of the hot fluid. The heat transfer fluid flows through a conduit in the base assembly 142 and then returns to the HTX 177. HTX raises or lowers the temperature of the heat transfer fluid, and the fluid then returns to the base assembly through the circuit.

The HTX includes a heater 186 to heat a heat transfer fluid, thereby heating the substrate. The heater may be formed using a resistance coil around a tube within the heat exchanger (or with the heat exchanger), where the heating fluid conducts heat through the exchanger to a conduit containing the hot fluid. The HTX also includes a cooler 188 that draws heat from the hot fluid. This can be accomplished by using a radiator to throw heat into ambient air or a cooling fluid, or by any of a variety of other means. The heater and cooler may be combined such that the temperature control fluid is first heated or cooled, and then the heat of the control fluid is exchanged with the heat fluid in the heat transfer fluid circuit.

The temperature controller 175 may control a valve (or other flow control device) between the HTX 177 and the fluid conduit in the base assembly 142 to control the rate of heat transfer fluid flow to the fluid circuit. The temperature controller 175, temperature sensor, and valve can be combined to simplify setup and operation procedures. In various embodiments, after the heat transfer fluid returns from the fluid conduit, the heat exchanger senses the temperature of the heat transfer fluid and heats or cools the heat transfer fluid based on the temperature of the fluid and the temperature required for the operating state of the chamber 102.

An electric heater (not shown) can also be used in the base assembly to apply heat to the base assembly. An electric heater (typically in the form of a resistive element) is coupled to a power supply 179, which is controlled by a temperature control system 175 to recharge the heater element to obtain the desired temperature.

The heat transfer fluid may be a liquid such as (but not limited to) deionized water / glycol, a fluorinated coolant (such as Fluorinert® from 3M or Galden® from Solvay Solexis), or any other suitable dielectric fluid (Such as a dielectric fluid containing a perfluorinated inert polyether). Although this specification describes a pedestal in the context of a PECVD processing chamber, the pedestals described herein can be used in a variety of different chambers and can be used in a variety of different processes.

A backside gas source 178, such as a pressurized gas supply or pump and a gas storage tank, is coupled to the suction cup assembly 142 through a mass flow meter 185 or other type of valve. The backside gas can be helium, argon, or a gas that provides thermal convection between the wafer and the disk without affecting the chamber process. Controlled by a system controller 170 connected to the system, the gas source pumps the gas to the backside of the wafer through the base assembly gas outlet described in more detail below.

The processing system 100 may also include other systems not specifically shown in FIG. 7, such as a plasma source, a vacuum pump system, an access door, a micro-machining, a laser system, and an automated processing system. The illustrated chamber is provided as an example, and any of a variety of other chambers can be used with the present invention, depending on the nature of the workpiece and the desired process. The illustrated base and thermal fluid control system can be adapted for use with different solid chambers and processes.

The use of the singular forms "a", "an", and "the" in this specification and the scope of the appended patents are intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein represents and includes any and all possible combinations of one or more of the associated listed items.

The terms "coupled" and "connected," as well as their derivatives, can be used herein to describe functional or structural relationships between components. It should be understood that these terms are not intended as synonyms for each other. In contrast, in a specific embodiment, “connected” may be used to indicate that two or more elements are in direct physical, optical, or electrical contact with each other. "Coupled" can be used to indicate that two or more elements are in direct, indirect (ie, with other intervening elements) contacting each other physically, optically, or electrically, and / or that the two or more elements are common Manipulate or interact with each other (for example, in a causal relationship).

The terms "over", "under", "between" and "on" as used herein refer to the relative position of one component or material layer relative to other components or layers When such entity relationships are worthy of discussion. For example, in the background content of a material layer, a layer placed above or below another layer may directly contact this other layer or may have one or more intervening layers. Furthermore, a layer placed between two layers may directly contact the two layers, or may have one or more intervening layers. In contrast, the first layer "on" the second layer is in direct contact with this second layer. I want to make a similar distinction in the background of the components.

It should be understood that the above description is intended to be exemplary rather than limiting. For example, although the flowcharts in the figures show a particular order of operations performed by certain embodiments of the invention, it should be understood that this order is not required (for example, alternative embodiments may be in Combine certain operations, override certain operations, etc. to perform a job). Furthermore, upon reading and understanding the above description, many other specific embodiments will be apparent to those having ordinary knowledge in the field of the present invention. Although the present invention has been described with reference to specific exemplary embodiments, it should be recognized that the present invention is not limited to the specific embodiments described, but may be modified and changed within the spirit and scope of the scope of additional patent applications. Therefore, the scope of the present invention should be determined with reference to the scope of additional patent applications, and include the complete and equal scope of these patent application scopes.

Examples of different specific embodiments of a two-electrode system include an ESC with dual DC electrodes in a top plate, where the two electrodes are spaced apart and connected to a power supply.

A specific embodiment includes the aforementioned design, in which an electrostatic force of ESC is generated by an upper electrode with two electrodes close to the top surface of the disc, and the upper electrode is charged by applying a voltage to the upper electrode.

A specific embodiment includes the aforementioned design, wherein each electrode is formed of a line grid.

Particular embodiments include the aforementioned design, where the grid is a network of generally orthogonal crossing lines.

A specific embodiment includes the aforementioned design, including an aluminum base plate connected to an RF generator.

Specific embodiments include the aforementioned design, in which the lower electrode is electrically connected to the voltage supply through a series of studs which are attached between the upper electrode and the lower electrode and carry the same voltage potential.

Specific embodiments include the aforementioned design, wherein there are channels, holes, and / or gaps in the area between the upper electrode and the lower electrode.

Specific embodiments include the aforementioned design, where any channels, holes, and gaps in the area between the upper and lower electrodes will be shielded from any charges built up by the upper and lower grids.

Particular embodiments include the aforementioned design, wherein the electrodes are connected to the power supply by a conductive rod.

The specific embodiment includes the foregoing design, wherein the rod has a high-resistance section and a low-resistance section, the high-resistance section has a resistance value greater than 1K ohm and is closest to the electrode, and the low-resistance section has, for example, less than 1K ohm The resistance value is closest to the power supply.

A specific embodiment includes the aforementioned design, wherein the high-resistivity portion is made of a mixture of aluminum and alumina particles.

Specific embodiments include means for performing the functions of any of the foregoing specific embodiments.

A specific embodiment includes a method for processing a workpiece in a plasma processing chamber, including driving an electrode in a top plate of an electrostatic chuck to a first voltage to hold the workpiece, a first electrode system close to a top surface of the top plate, and A second electrode in the top plate is driven to a first voltage to form a Faraday cage within the top plate.

Specific embodiments include the aforementioned design, where the electrodes are also driven to radio frequency to bias the plasma in the chamber.

100‧‧‧ Plasma System
102‧‧‧Processing chamber body
103‧‧‧Power socket or power box
104‧‧‧ chamber cover
106‧‧‧shield ring
108‧‧‧Gas distribution system
112‧‧‧ sidewall
116‧‧‧ bottom wall
120‧‧‧ processing area
122‧‧‧channel
124‧‧‧channel
125‧‧‧Circular pump cavity
126‧‧‧axis
127‧‧‧ chamber liner assembly
128‧‧‧base
129‧‧‧base assembly
130‧‧‧ par
131‧‧‧Exhaust port
135‧‧‧Circular ring
140‧‧‧Gas inlet channel
141‧‧‧heat transfer fluid circuit
142‧‧‧Sprinkler head assembly
143‧‧‧Temperature reading
144‧‧‧Barrier
146‧‧‧Barrier
147‧‧‧cooling channel
148‧‧‧ ring base plate
158‧‧‧Dielectric isolator
160‧‧‧ transfer port
161‧‧‧ substrate lifting pin
164‧‧‧Pump system
165‧‧‧RF source
170‧‧‧System Controller
172‧‧‧Central Processing Unit
173‧‧‧Memory
174‧‧‧Input / output interface
175‧‧‧Temperature Controller
177‧‧‧Heat exchanger
178‧‧‧Backside gas source
179‧‧‧ Power Supply
185‧‧‧mass flow rate meter
186‧‧‧heater
188‧‧‧ cooler
202‧‧‧ cooling plate
204‧‧‧ Dielectric Adhesive Layer
206‧‧‧Disc
208‧‧‧Workpiece
210‧‧‧lower electrode
212‧‧‧up electrode
214‧‧‧Stud
220‧‧‧par
222‧‧‧External Power Supply
224‧‧‧External RF (radio frequency) power supply
230‧‧‧ Central tube
232‧‧‧ Extra hole
240‧‧‧ Upper Part
242‧‧‧Next
260‧‧‧ connector rod
262‧‧‧par
302‧‧‧ substrate
304‧‧‧ Dielectric Adhesive Layer
306‧‧‧Disc
308‧‧‧wafer
310‧‧‧electrostatic electrode
312‧‧‧electrostatic electrode
314‧‧‧Stud
320‧‧‧ par
322‧‧‧Voltage source
324‧‧‧RF Power Supply
326‧‧‧electrical connector
330‧‧‧ Central Stomata
332‧‧‧Lift pin hole
402‧‧‧Aluminum base plate
404‧‧‧Adhesive layer
406‧‧‧ceramic disc
410‧‧‧ under grid
412‧‧‧on grid
414‧‧‧Studs
420‧‧‧par
422‧‧‧Voltage source
424‧‧‧Second RF Power Supply
426‧‧‧electrical connector
430‧‧‧ Central Stomata
432‧‧‧Lift pin hole
440‧‧‧DC voltage
502‧‧‧ base plate
506‧‧‧Top plate
510‧‧‧lower electrode
512‧‧‧up electrode
514‧‧‧vertical studs
520‧‧‧par
522‧‧‧point of grid connecting rod
524‧‧‧Inductor
526‧‧‧electric insulator

The additional schematic examples illustrate specific embodiments of the present invention (and are not intended to be limiting), where:

FIG. 1 is a side cross-sectional view of an electrostatic chuck with a dual grid electrode according to a specific embodiment of the present invention;

Figure 2 is a side cross-sectional view of an alternative electrostatic chuck with dual grid electrodes according to a specific embodiment of the present invention;

Figure 3 is a side cross-sectional view of yet another alternative electrostatic chuck with dual grid electrodes according to a specific embodiment of the present invention;

Figure 4 is a side cross-sectional view of yet another alternative electrostatic chuck with dual grid electrodes according to a specific embodiment of the present invention;

Figure 5 is a side cross-sectional view of yet another alternative electrostatic chuck with dual grid electrodes according to a specific embodiment of the present invention;

FIG. 6 is a side sectional view of an example of the electrical connector of FIG. 1 according to a specific embodiment of the present invention; FIG.

FIG. 7 is a partially transparent top view of the disc of FIG. 1 according to a specific embodiment of the present invention, illustrating various holes;

FIG. 8 is a side sectional view of an electrostatic chuck with a reinforcing rod according to a specific embodiment of the present invention; and

FIG. 9 is a schematic diagram of a plasma etching system including a workpiece carrier according to a specific embodiment of the present invention.

Domestic hosting information (please note in order of hosting institution, date, and number) None

Information on foreign deposits (please note in order of deposit country, institution, date, and number) None

(Please change pages to record separately) None

202‧‧‧ cooling plate

204‧‧‧ Dielectric Adhesive Layer

206‧‧‧Disc

208‧‧‧Workpiece

210‧‧‧lower electrode

212‧‧‧up electrode

214‧‧‧Stud

220‧‧‧par

222‧‧‧External Power Supply

224‧‧‧External RF (Radio Frequency) Power Supply

230‧‧‧ Central tube

232‧‧‧ Extra hole

262‧‧‧par

Claims (20)

An electrostatic chuck includes: a base plate; a top plate; a first electrode, the first electrode is located in the top plate and is adjacent to the top surface of the top plate to electrostatically hold a workpiece; and a second electrode, the first electrode Two electrodes are in the top plate and spaced from the first electrode. The first electrode and the second electrode are coupled to a power supply to charge the first electrode with static electricity. The sucker according to claim 1, wherein the power supply provides DC power to the first electrode and the second electrode. The suction cup according to claim 2, wherein the power supply further provides an alternating current to the first electrode to cause a bias voltage on the workpiece. The chuck according to claim 1, wherein the base plate is attached to the top plate by a dielectric adhesive. As described in claim 1, the suction cup further includes a plurality of conductive studs for electrically connecting the first electrode to the second electrode. The suction cup according to claim 5, wherein the first electrode and the second electrode are formed of a conductive mesh. The suction cup according to claim 5, wherein the top plate is ceramic, and the electrodes and studs are embedded in the ceramic. The suction cup according to claim 1, further comprising a power supply coupled to the base plate to apply a DC voltage to the base plate, the DC voltage having the same polarity as the voltage applied to the first electrode. The polarity of the DC voltage with the second electrode. The chuck according to claim 1, wherein the DC voltage applied to the base plate is approximately half of the DC voltage applied to the electrodes. The sucker according to claim 1, wherein the first electrode and the second electrode are coupled to the power supply through a rod coupled to the second electrode, and wherein a plurality of conductive studs will come from the power supply The power of the device is electrically connected from the second electrode to the first electrode. The sucker according to claim 1, wherein at least one of the first electrode and the second electrode is coupled to the power supply through a rod having a high resistance value section and a low resistance value section The high resistance value section is coupled to the electrode, and the low resistance value section is coupled to the power supply. The suction cup according to claim 1, wherein at least one of the first electrode and the second electrode is coupled to the power supply through a rod, the rod extends through the base plate, and the rod has a base plate An inductor inside. The sucker according to claim 12, wherein the inductor has an inductance value to choke the RF current generated in the top plate by an applied RF plasma. The suction cup according to claim 1, wherein the base plate includes a cooling channel to load a coolant to cool the workpiece. The sucker according to claim 1, wherein any channels, holes and gaps in a region between the first electrode and the second electrode will be shielded from the charges established by the first electrode and the low electrode. A method for processing a workpiece in a plasma processing chamber includes the following steps: a step of driving a first electrode, driving an electrode in a top plate of an electrostatic chuck to a first voltage to hold the workpiece, The first electrode is located near a top surface of the top plate; and a step of driving a second electrode to drive a second electrode in the top plate to the first voltage to form a Faraday with the first electrode in the top plate. cage. The method of claim 16 further comprising the steps of: driving the electrodes to a radio frequency to bias the workpiece in the chamber. A plasma processing chamber includes: a plasma chamber; a plasma source for generating a plasma containing gas ions in the plasma chamber; and an electrostatic chuck including a base plate A top plate, a first electrode, and a second electrode, the first electrode in the top plate is adjacent to the top surface of the top plate to electrostatically hold a workpiece, and the second electrode is spaced from the first electrode in the top plate On, the first electrode and the second electrode are coupled to a power supply, and the first electrode is electrostatically charged. The chamber of claim 18, the carrier further comprising a support plate below the cooling plate, the support plate being configured to be connected to a gas line to supply the pressurized gas to a cooling air hole. The chamber according to claim 18 or 19, wherein at least one of the first electrode and the second electrode is coupled to the power supply through a rod having a high resistance value section and a low resistance And an inductor, the high resistance value section is coupled to the electrode, the low resistance value section is coupled to the power supply, and the inductor is located in the substrate.